The present invention relates to liquid detergent products which are adapted for home laundry machine washing of fabrics. More specifically the present invention relates to heavy duty liquid laundry detergent products which exhibit superior freeze/thaw and high/low temperature stability.
Compared with powder-form detergents, liquid detergents have handling advantages and other performance features. In particular, larger quantities of nonionic surfactants can be incorporated in liquid detergents than in powder-form detergents, which has the advantage of greater effectiveness against oily and greasy soil.
A water-based liquid detergent which contains a mixture of anionic and nonionic surfactants, and in which the nonionic surfactant is 20% or more of the liquid detergent, generally lacks homogeneity and typically undergoes phase separation. As another disadvantage, liquid detergents of this type often exhibit a higher viscosity than is desirable for normal laundry usage.
Further to liquid laundry detergent compositions, the incorporation of a major amount of detergent builder poses a significant formulation challenge since the presence of a major quantity of detergent builder inevitably causes the detergent composition to phase separate. Liquid detergent formulations that contain a detergent builder ingredient require careful control of the surfactant to builder ratio so as to prevent salting-out of the surfactant phase.
In another aspect, liquid laundry detergent compositions are susceptible to instability under extended freeze/thaw and high/low temperature conditions.
A variety of improved types of liquid detergent compositions are described in publications such as U.S. Pats. No. 3,929,680; 4,092,273; 4,105,592; 4,110,262; 4,201,686; 4,368,147; 4,490,285; 4,671,895; 4,747,977; 5,049,302; 5,132,053; 5,205,960; 5,215,683; 5,403,516; 5,409,629; 5,500,151; 5,529,724; 5,536,440; and 5,597,507; incorporated by reference.
There remains a continuing interest in the development of improved liquid detergent compositions which overcome one or more inherent disadvantages associated with liquid detergent products.
Accordingly, it is an object of this invention to provide a heavy duty liquid detergent composition which contains a high level of active surfactant ingredients.
It is another object of this invention to provide a liquid laundry detergent product which has a content of detergent builder, and which has clarity and stability without the inclusion of a hydrotrope constituent.
It is a further object of this invention to provide a liquid laundry detergent product which provides high detergency under fabric washing conditions, and which exhibits freeze/thaw and high/low temperature stability.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.